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1.
Arch Virol ; 165(2): 331-343, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31832864

RESUMO

The most characteristic feature of the hepatitis C virus (HCV) genome in patients with chronic hepatitis C is its remarkable variability and diversity. To better understand this feature, we performed genetic analysis of HCV replicons recovered from two human hepatoma HuH-7-derived cell lines after 1, 3, 5, 7, and 9 years in culture: The cell lines 50-1 and sO harbored HCV 1B-1 and O strain-derived HCV replicons established in 2002 and 2003, respectively. The results revealed that genetic variations in both replicons accumulated in a time-dependent manner at a constant rate despite the maintenance of moderate diversity (less than 1.8% difference) between the clones and that the mutation rate in the 50-1 and sO replicons was 2.5 and 2.9 × 10-3 base substitutions/site/year, respectively. We found that the genetic distance of both replicons increased from 7.9% to 10.5% after 9 years in culture. In addition, we observed that the guanine + cytosine (GC) content of both replicon RNAs increased in a time-dependent manner, as observed in our previous studies. Finally, we demonstrated that the high sensitivity of both replicons to direct-acting antivirals was maintained even after 9 years in culture. Our results suggest that long-term cultured HCV replicon-harboring cells are a useful model for understanding the variability and diversity of the HCV genome and the drug sensitivity of HCV in patients with chronic hepatitis C.


Assuntos
Variação Genética/genética , Hepacivirus/genética , Replicação Viral/genética , Carcinoma Hepatocelular/virologia , Técnicas de Cultura de Células , Linhagem Celular Tumoral , Genes Reporter/genética , Genoma Viral/genética , Genótipo , Hepatite C Crônica/virologia , Humanos , Neoplasias Hepáticas/virologia , RNA Viral/genética , Replicon/genética
2.
PLoS Genet ; 15(9): e1008320, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31513569

RESUMO

In all kingdoms of life, DNA is used to encode hereditary information. Propagation of the genetic material between generations requires timely and accurate duplication of DNA by semiconservative replication prior to cell division to ensure each daughter cell receives the full complement of chromosomes. DNA synthesis of daughter strands starts at discrete sites, termed replication origins, and proceeds in a bidirectional manner until all genomic DNA is replicated. Despite the fundamental nature of these events, organisms have evolved surprisingly divergent strategies that control replication onset. Here, we discuss commonalities and differences in replication origin organization and recognition in the three domains of life.


Assuntos
Replicação do DNA/genética , Replicação do DNA/fisiologia , Origem de Replicação/genética , Evolução Biológica , Divisão Celular/genética , Cromossomos/genética , Evolução Molecular , Replicon/genética
3.
Mol Biol (Mosk) ; 53(4): 600-612, 2019.
Artigo em Russo | MEDLINE | ID: mdl-31397434

RESUMO

A new plasmid, pSM22, was isolated from Serratia marcescens and sequenced. Its 43 190-bp sequence with an average GC-content of 58% contains 31 open reading frames (ORFs) which form replication, conjugation, stability, and adaptive modules. The replication module includes a site of initiation of leading-strand synthesis in plasmid replication, a replication termination site (terC), the rep A (=repA1) and repA4 genes, and the copA sequence, which codes for an antisense RNA (asRNA). These structures are functionally integrated in an FII replicon (incompatibility group IncFII). Based on the significant differences between the FII replicon and the canonical sequences of the R plasmids R1 and NR1 (=R100=R222), pSM22 was assigned to a new subtype. The conjugation module includes 13 genes with a high identity to the genes responsible for conjugation of the F plasmid. A comparative genomic analysis showed that the conjugation modules of pSM22 and F are structurally similar. By the conjugation system and the presence of three conserved motifs in relaxase (TraI), pSM22 belongs to the F12 clade of the MOBF type. The stability module includes the resD and parA genes, which are responsible for the resolution of multimeric plasmid forms and their subsequent segregation between daughter cells. The adaptive module contains the microcin H47 (MccH47) secretion/processing and UV resistance genes. The mosaic structure of pSM22 and reductive evolution of its modules suggest high genomic plasticity for the genus Serratia. An analysis of the architecture of the pSM22 modules clarifies the evolutionary relationships among IncF/MOBF12 group plasmids in bacteria of the family Enterobacteriaceae and opens a novel avenue for further comparative genomic studies of Serratia plasmids.


Assuntos
Evolução Molecular , Genômica , Plasmídeos/classificação , Plasmídeos/genética , Replicação do DNA , Genes Bacterianos , Genoma Bacteriano/genética , Replicon/genética , Serratia marcescens/genética
4.
Nucleic Acids Res ; 47(15): 8061-8083, 2019 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-31276592

RESUMO

Zinc finger antiviral protein (ZAP) is a powerful restriction factor for viruses with elevated CpG dinucleotide frequencies. We report that ZAP similarly mediates antiviral restriction against echovirus 7 (E7) mutants with elevated frequencies of UpA dinucleotides. Attenuation of both CpG- and UpA-high viruses and replicon mutants was reversed in ZAP k/o cell lines, and restored by plasmid-derived reconstitution of expression in k/o cells. In pull-down assays, ZAP bound to viral RNA transcripts with either CpG- and UpA-high sequences inserted in the R2 region. We found no evidence that attenuation of CpG- or UpA-high mutants was mediated through either translation inhibition or accelerated RNA degradation. Reversal of the attenuation of CpG-high, and UpA-high E7 viruses and replicons was also achieved through knockout of RNAseL and oligodenylate synthetase 3 (OAS3), but not OAS1. WT levels of replication of CpG- and UpA-high mutants were observed in OAS3 k/o cells despite abundant expression of ZAP, indicative of synergy or complementation of these hitherto unconnected pathways. The dependence on expression of ZAP, OAS3 and RNAseL for CpG/UpA-mediated attenuation and the variable and often low level expression of these pathway proteins in certain cell types, such as those of the central nervous system, has implications for the use of CpG-elevated mutants as attenuated live vaccines against neurotropic viruses.


Assuntos
2',5'-Oligoadenilato Sintetase/metabolismo , Endorribonucleases/metabolismo , Regulação da Expressão Gênica , Proteínas de Ligação a RNA/metabolismo , Transdução de Sinais , 2',5'-Oligoadenilato Sintetase/genética , Células A549 , Linhagem Celular Tumoral , Ilhas de CpG/genética , Fosfatos de Dinucleosídeos/genética , Endorribonucleases/genética , Enterovirus Humano B/genética , Técnicas de Inativação de Genes , Humanos , Mutação , Ligação Proteica , RNA Viral/genética , RNA Viral/metabolismo , Proteínas de Ligação a RNA/genética , Replicon/genética
5.
Nucleic Acids Res ; 47(17): 9296-9312, 2019 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-31350895

RESUMO

Chikungunya virus (CHIKV) is a re-emerging, pathogenic Alphavirus transmitted to humans by Aedes spp. mosquitoes. We have mapped the RNA structure of the 5' region of the CHIKV genome using selective 2'-hydroxyl acylation analysed by primer extension (SHAPE) to investigate intramolecular base-pairing at single-nucleotide resolution. Taking a structure-led reverse genetic approach, in both infectious virus and sub-genomic replicon systems, we identified six RNA replication elements essential to efficient CHIKV genome replication - including novel elements, either not previously analysed in other alphaviruses or specific to CHIKV. Importantly, through a reverse genetic approach we demonstrate that the replication elements function within the positive-strand genomic copy of the virus genome, in predominantly structure-dependent mechanisms during efficient replication of the CHIKV genome. Comparative analysis in human and mosquito-derived cell lines reveal that a novel element within the 5'UTR is essential for efficient replication in both host systems, while those in the adjacent nsP1 encoding region are specific to either vertebrate or invertebrate host cells. In addition to furthering our knowledge of fundamental aspects of the molecular virology of this important human pathogen, we foresee that results from this study will be important for rational design of a genetically stable attenuated vaccine.


Assuntos
Febre de Chikungunya/genética , Vírus Chikungunya/genética , Proteínas não Estruturais Virais/genética , Replicação Viral/genética , Aedes/virologia , Animais , Febre de Chikungunya/virologia , Vírus Chikungunya/patogenicidade , Genoma Viral/genética , Humanos , RNA Viral/genética , Replicon/genética
6.
BMC Res Notes ; 12(1): 422, 2019 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-31311578

RESUMO

OBJECTIVES: Plasmids harbour antibiotic resistance genes which contribute to the emergence of multidrug resistant pathogens. We detected the presence of plasmids in multidrug resistant Salmonella enterica serovar Typhi (S. Typhi) isolates from our previous study and consequently determined their incompatibility groups and possibility of conjugation transmission. Plasmids were extracted from 98 multidrug resistant S. Typhi isolates based on alkaline lysis technique. Plasmid incompatibility grouping was established by PCR replicon typing using 18 pairs of primers to amplify FIA, FIB, FIC, HI1, HI2, I1-Iγ, L/M, N, P, W, T, A/C, K, B/O, X, Y, F and FIIA replicons. Antibiotic resistance phenotypes were conjugally transferred from S. Typhi isolates with plasmids to Escherichia coli K12F strain devoid of plasmids. RESULTS: Approximately 79.6% of the MDR S. Typhi isolates were related to the existence of plasmids. We detected 93.6% of plasmids belonging to incompatibility (Inc) group HI1. The other incompatibility groups identified included IncFIC (16.7%), IncP (1.3%), and IncI1 (1.3%) which appeared together with Inc HI1. MDR S. Typhi isolated carried a homologous plasmid of incompatibility group HI1 most of which transferred the resistance phenotypes of ampicillin, tetracycline and chloramphenicol to the transconjugants.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Plasmídeos/genética , Salmonella typhi/efeitos dos fármacos , Ampicilina/farmacologia , Cloranfenicol/farmacologia , Conjugação Genética/genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Humanos , Quênia , Testes de Sensibilidade Microbiana , Replicon/genética , Salmonella typhi/classificação , Salmonella typhi/genética , Tetraciclina/farmacologia , Febre Tifoide/microbiologia
7.
Microb Genom ; 5(7)2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31170060

RESUMO

Pseudomonas aeruginosa is a highly versatile, antibiotic-resistant Gram-negative bacterium known for causing opportunistic infections and contamination of industrial products. Despite extensive genomic analysis of clinical P. aeruginosa strains, no genomes exist for preservative-tolerant industrial strains. A unique collection of 69 industrial isolates was assembled and compared to clinical and environmental strains; 16 genetically distinct industrial strains were subjected to array tube genotyping, multilocus sequence typing and whole-genome sequencing. The industrial strains possessed high preservative tolerance and were dispersed widely across P. aeruginosa as a species, but recurrence of strains from the same lineage within specific industrial products and locations was identified. The industrial P. aeruginosa genomes (mean=7.0 Mb) were significantly larger than those of previously sequenced environmental (mean=6.5 Mb; n=19) and clinical (mean=6.6 Mb; n=66) strains. Complete sequencing of the P. aeruginosa industrial strain RW109, which encoded the largest genome (7.75 Mb), revealed a multireplicon structure including a megaplasmid (555 265 bp) and large plasmid (151 612 bp). The RW109 megaplasmid represented an emerging plasmid family conserved in seven industrial and two clinical P. aeruginosa strains, and associated with extremely stress-resilient phenotypes, including antimicrobial resistance and solvent tolerance. Here, by defining the detailed phylogenomics of P. aeruginosa industrial strains, we show that they uniquely possess multireplicon, megaplasmid-bearing genomes, and significantly greater genomic content worthy of further study.


Assuntos
Farmacorresistência Bacteriana/genética , Genoma Bacteriano/genética , Plasmídeos/genética , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/isolamento & purificação , DNA Bacteriano/genética , Humanos , Microbiologia Industrial , Filogenia , Replicon , Sequenciamento Completo do Genoma
8.
EcoSal Plus ; 8(2)2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31187729

RESUMO

Plasmids are ubiquitous in the microbial world and have been identified in almost all species of bacteria that have been examined. Their localization inside the bacterial cell has been examined for about two decades; typically, they are not randomly distributed, and their positioning depends on copy number and their mode of segregation. Low-copy-number plasmids promote their own stable inheritance in their bacterial hosts by encoding active partition systems, which ensure that copies are positioned in both halves of a dividing cell. High-copy plasmids rely on passive diffusion of some copies, but many remain clustered together in the nucleoid-free regions of the cell. Here we review plasmid localization and partition (Par) systems, with particular emphasis on plasmids from Enterobacteriaceae and on recent results describing the in vivo localization properties and molecular mechanisms of each system. Partition systems also cause plasmid incompatibility such that distinct plasmids (with different replicons) with the same Par system cannot be stably maintained in the same cells. We discuss how partition-mediated incompatibility is a consequence of the partition mechanism.


Assuntos
Enterobacteriaceae/genética , Plasmídeos/genética , Proteínas de Bactérias/genética , Enterobacteriaceae/metabolismo , Replicon
9.
J Gen Virol ; 100(6): 1038-1051, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31107197

RESUMO

Geminiviruses are a group of small plant viruses responsible for devastating crop damage worldwide. The emergence of agricultural diseases caused by geminiviruses is attributed in part to their high rates of recombination, leading to complementary function between viral components across species and genera. We have developed a mastreviral reporter system based on bean yellow dwarf virus (BeYDV) that replicates to high levels in the plant nucleus, expressing very high levels of GFP. To investigate the potential for complementation of movement function by other geminivirus genera, the movement protein (MP) and nuclear shuttle protein (NSP) from the bipartite begomovirus Bean dwarf mosaic virus (BDMV) were produced and characterized in Nicotiana benthamiana leaves. While overexpression of MP and NSP strongly inhibited GFP expression from the mastreviral reporter and caused adverse plant symptoms, optimizing the expression levels of MP and NSP allowed functional cell-to-cell movement. Hybrid virus vectors were created that express BDMV MP and NSP from mastreviral replicons, allowing efficient cell-to-cell movement comparable to native BDMV replicons. We find that the expression levels of MP and NSP must be fine-tuned to provide sufficient MP/NSP for movement without eliciting the plant hypersensitive response or adversely impacting gene expression from viral replicons. The ability to confer cell-to-cell movement to mastrevirus replicons depended strongly on replicon size: 2.1-2.7 kb replicons were efficiently moved, while 3 kb replicons were inhibited, and 3.9 kb replicons were very strongly inhibited. Optimized expression of MP/NSP from the normally phloem-limited Abutilon mosaic virus (AbMV) allows efficient movement in non-phloem cells.


Assuntos
Begomovirus/genética , Movimento Celular/genética , Proteínas Nucleares/genética , Folhas de Planta/virologia , Tabaco/virologia , Transporte Biológico/genética , Núcleo Celular/genética , Proteínas do Movimento Viral em Plantas/genética , Replicon/genética
10.
Environ Pollut ; 251: 146-154, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31078086

RESUMO

A comparative study was conducted to (1) assess the potential of raw sewage used for urban agriculture to disseminate bacterial resistance in two cities of different size in Cameroon (Central Africa) and (2) compare the outcome with data obtained in Burkina Faso (West Africa). In each city, raw sewage samples were sampled from open-air canals in three neighbourhoods. After DNA extraction, the microbial population structure and function, presence of pathogens, antibiotic resistance genes and Enterobacteriaceae plasmids replicons were analysed using whole genome shotgun sequencing and bioinformatics. Forty-three pathogen-specific virulenc e factor genes were detected in the sewage. Eighteen different incompatibility groups of Enterobacteriaceae plasmid replicon types (ColE, A/C, B/O/K/Z, FIA, FIB, FIC, FII, H, I, N, P, Q, R, T, U, W, X, and Y) implicated in the spread of drug-resistance genes were present in the sewage samples. One hundred thirty-six antibiotic resistance genes commonly associated with MDR plasmid carriage were identified in both cities. Enterobacteriaceae plasmid replicons and ARGs found in Burkina Faso wastewaters were also present in Cameroon waters. The abundance of Enterobacteriaceae, plasmid replicons and antibiotic resistance genes was greater in Yaounde, the city with the greater population. In conclusion, the clinically relevant environmental resistome found in raw sewage used for urban agriculture is common in West and Central Africa. The size of the city impacts on the abundance of drug-resistant genes in the raw sewage while ESBL gene abundance is related to the prevalence of Enterobacteriaceae along with plasmid Enterobacteriaceae abundance associated to faecal pollution.


Assuntos
Agricultura , Resistência Microbiana a Medicamentos/genética , Genes Microbianos , Esgotos/microbiologia , Burkina Faso , Camarões , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Enterobacteriaceae , Monitoramento Ambiental , Plasmídeos , Densidade Demográfica , Replicon , Eliminação de Resíduos Líquidos , Águas Residuárias
11.
mBio ; 10(3)2019 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-31138741

RESUMO

Prokaryotes represent an ancestral lineage in the tree of life and constitute optimal resources for investigating the evolution of genomes in unicellular organisms. Many bacterial species possess multipartite genomes offering opportunities to study functional variations among replicons, how and where new genes integrate into a genome, and how genetic information within a lineage becomes encoded and evolves. To analyze these issues, we focused on the model soil bacterium Sinorhizobium meliloti, which harbors a chromosome, a chromid (pSymB), a megaplasmid (pSymA), and, in many strains, one or more accessory plasmids. The analysis of several genomes, together with 1.4 Mb of accessory plasmid DNA that we purified and sequenced, revealed clearly different functional profiles associated with each genomic entity. pSymA, in particular, exhibited remarkable interstrain variation and a high density of singletons (unique, exclusive genes) featuring functionalities and modal codon usages that were very similar to those of the plasmidome. All this evidence reinforces the idea of a close relationship between pSymA and the plasmidome. Correspondence analyses revealed that adaptation of codon usages to the translational machinery increased from plasmidome to pSymA to pSymB to chromosome, corresponding as such to the ancestry of each replicon in the lineage. We demonstrated that chromosomal core genes gradually adapted to the translational machinery, reminiscent of observations in several bacterial taxa for genes with high expression levels. Such findings indicate a previously undiscovered codon usage adaptation associated with the chromosomal core information that likely operates to improve bacterial fitness. We present a comprehensive model illustrating the central findings described here, discussed in the context of the changes occurring during the evolution of a multipartite prokaryote genome.IMPORTANCE Bacterial genomes usually include many thousands of genes which are expressed with diverse spatial-temporal patterns and intensities. A well-known evidence is that highly expressed genes, such as the ribosomal and other translation-related proteins (RTRPs), have accommodated their codon usage to optimize translation efficiency and accuracy. Using a bioinformatic approach, we identify core-genes sets with different ancestries, and demonstrate that selection processes that optimize codon usage are not restricted to RTRPs but extended at a genome-wide scale. Such findings highlight, for the first time, a previously undiscovered adaptation strategy associated with the chromosomal-core information. Contrasted with the translationally more adapted genes, singletons (i.e., exclusive genes, including those of the plasmidome) appear as the gene pool with the less-ameliorated codon usage in the lineage. A comprehensive summary describing the inter- and intra-replicon heterogeneity of codon usages in a complex prokaryote genome is presented.


Assuntos
Cromossomos Bacterianos , Evolução Molecular , Genoma Bacteriano , Sinorhizobium meliloti/genética , Biologia Computacional , DNA Ribossômico/genética , Genes Bacterianos , Plasmídeos/genética , Replicon
12.
Virology ; 533: 86-92, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31136895

RESUMO

Duck Tembusu virus (DTMUV) is a novel flavivirus that has caused an outbreak of severe duck egg-drop syndrome since 2010. It has spread rapidly to other avian species, causing enormous economic loss. In the present study, we generated a reporter virus expressing NanoLuc luciferase, which was stable after 10 rounds of continuous propagation without reporter gene deletion. Moreover, we generated two types of replicons driven by the T7 promoter or CMV promoter, both of which worked well in BHK21 cells. Furthermore, we developed the first packaging system for DTMUV by co-transfection into BHK21 cells of a replicon (containing mature C) and a plasmid encoding C16-prM-E, which resulted in the production of single round infectious particles (SRIPs). We also generated a packaging cell line for DTMUV to produce SRIPs. We believe that these multicomponent platform tools are important for DTMUV pathogenesis research and novel vaccine development.


Assuntos
Infecções por Flavivirus/veterinária , Flavivirus/genética , Doenças das Aves Domésticas/virologia , Replicon , Animais , Patos , Flavivirus/fisiologia , Infecções por Flavivirus/virologia , Genes Reporter , Luciferases/genética , Luciferases/metabolismo , Genética Reversa
13.
Hum Antibodies ; 27(3): 185-191, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30958341

RESUMO

BACKGROUND AND AIMS: Although HCV is one of the major health problems worldwide with the highest prevalence of genotype 4a in Egypt, it is poorly understood because of the limitations of having a robust in vitro model that allows the investigation and understanding of viral pathogenesis and life cycle. Genomic replicons for HCV are widely used and proved to have strong replication efficiency in cell culture, however, they are not able to produce infectious particles to enable the investigation of the whole viral life cycle and they mostly represent few sub-genomic classes for HCV. Hence, Genotype specific replication system is necessary to address specific sub-genomic phenotypes related to Hepatitis C pathogenicity. METHODS: In this study we attempt to develop a sustainable co-culture model, which potentially provides essential route of infection for HCV by using HCV-positive sera from infected patients. In this novel in vitro model, we tested the viral replication in co-cultured Huh 7.5 and HepG2 cells in order to sustain full viral replication cycle. We used high viral load serum of HCV-infected patients (10 × 106 to 20 × 106 IU/ml) as a source for HCV particles to infect co-cultured cells for 7 days. RESULTS AND CONCLUSIONS: Viral replication capacity was increased 3-5 folds in the coculture condition compared to the individual cell lines, which indicates an improvement to viral infectivity in vitro. SIGNIFICANCE STATEMENT: This novel coculture system represents a new in vitro model that will help study the underlying mechanisms of HCV pathogenicity.


Assuntos
Técnicas de Cocultura/métodos , Hepacivirus/genética , Soro/virologia , Replicação Viral/genética , Linhagem Celular Tumoral , Egito , Genótipo , Células Hep G2 , Hepatite C/virologia , Humanos , RNA Viral/genética , Replicon/genética , Carga Viral/genética
14.
Cells ; 8(4)2019 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-30934919

RESUMO

Mitophagy is a selective form of autophagy, targeting damaged mitochondria for lysosomal degradation. Although HCV infection has been shown to induce mitophagy, the precise underlying mechanism and the effector protein responsible remain unclear. Herein, we demonstrated that the HCV non-structural protein 5A (NS5A) plays a key role in regulating cellular mitophagy. Specifically, the expression of HCV NS5A in the hepatoma cells triggered hallmarks of mitophagy including mitochondrial fragmentation, loss of mitochondrial membrane potential, and Parkin translocation to the mitochondria. Furthermore, mitophagy induction through the expression of NS5A led to an increase in autophagic flux as demonstrated by an accumulation of LC3II in the presence of bafilomycin and a time-dependent decrease in p62 protein level. Intriguingly, the expression of NS5A concomitantly enhanced reactive oxygen species (ROS) production, and treatment with an antioxidant attenuated the NS5A-induced mitophagy event. These phenomena are similarly recapitulated in the NS5A-expressing HCV subgenomic replicon cells. Finally, we demonstrated that expression of HCV core, which has been documented to inhibit mitophagy, blocked the mitophagy induction both in cells harboring HCV replicating subgenomes or expressing NS5A alone. Our results, therefore, identified a new role for NS5A as an important regulator of HCV-induced mitophagy and have implications to broadening our understanding of the HCV-mitophagy interplay.


Assuntos
Hepacivirus/metabolismo , Dinâmica Mitocondrial , Proteínas não Estruturais Virais/metabolismo , Autofagia , Linhagem Celular Tumoral , Humanos , Lipídeos/química , Potencial da Membrana Mitocondrial , Proteínas Associadas aos Microtúbulos/metabolismo , Mitocôndrias/metabolismo , Transporte Proteico , Espécies Reativas de Oxigênio/metabolismo , Replicon/genética , Ubiquitina-Proteína Ligases/metabolismo
16.
Fish Shellfish Immunol ; 89: 378-383, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30978448

RESUMO

Viral replicon particles are single-cycle viruses defective for function(s) needed for viral replication, which allow them to be recognized as a safer form for the vaccination of animals compared to attenuated live viruses. However, deletion of genes that are critical for the induction of protective immunity can diminish the vaccine potential of viral replicon particles. Therefore, the manipulation of viral replicon particles to produce a molecular adjuvant can be a way to increase immunogenicity of vaccines based on viral replicon particles. Chemokines are a class of chemotactic cytokines that control the migration of diverse cells of vertebrates. CXC chemokine ligand 12 (CXCL12) binds to a receptor CXCR4, and CXCL12-CXCR4 signaling plays an important role in the migration of hematopoietic cells during embryogenesis and the attraction of leukocytes. In the present study, to evaluate the possible use of CXCL12 as a molecular adjuvant for an rVHSV-ΔG vaccine and to know differences between CXCL12a and CXCL12b in the adjuvant ability, we rescued VHSV replicon particles that are expressing olive flounder CXCL12a, CXCL12b, or eGFP (rVHSV-ΔG-CXCL12a, rVHSV-ΔG-CXCL12b, or rVHSV-ΔG-eGFP), and compared the ability to attract olive flounder leucocytes and to induce protection against a VHSV challenge. In the leukocytes migration assay, supernatants collected from cells infected with rVHSV-ΔG-CXCL12a and rVHSV-ΔG-CXCL12b showed significantly higher ability to attract olive flounder leukocytes than the supernatant of cells infected with rVHSV-ΔG-eGFP. Moreover, the significantly higher number of leukocytes were attracted to rVHSV-CXCL12a supernatant compared to rVHSV-CXCL12b supernatant, suggesting that CXCL12a would be more appropriate for the induction of immunity than CXCL12b in olive flounder. In the immunization experiment, olive flounder immunized with rVHSV-ΔG-CXCL12a showed significantly higher survival rate than fish immunized with rVHSV-ΔG-CXCL12b or rVHSV-ΔG-eGFP. In addition, fish immunized with rVHSV-ΔG-CXCL12a showed the highest serum neutralization activity. These results suggest the availability of CXCL12a for a molecular adjuvant of vaccines based on VHSV replicon particles.


Assuntos
Quimiocina CXCL12/imunologia , Doenças dos Peixes/prevenção & controle , Proteínas de Peixes/imunologia , Linguados/imunologia , Septicemia Hemorrágica Viral/prevenção & controle , Novirhabdovirus/imunologia , Vacinas Virais/administração & dosagem , Animais , Movimento Celular , Doenças dos Peixes/imunologia , Doenças dos Peixes/virologia , Septicemia Hemorrágica Viral/imunologia , Septicemia Hemorrágica Viral/virologia , Leucócitos/imunologia , Leucócitos/fisiologia , Distribuição Aleatória , Replicon/imunologia , Vacinas Virais/imunologia
17.
Fish Shellfish Immunol ; 88: 231-236, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30817994

RESUMO

Vaccines based on viral replicon particles would be advantageous to induce immune responses compared to inactivated viruses in that they can infect host cells (only once) and can produce viral proteins in the infected cells like live viruses. Furthermore, as viral replicon particles are replication-defective, they are safer than live attenuated viruses. Previously, we had rescued viral hemorrhagic septicemia virus (VHSV) replicon particles lacking full ORF of G gene (rVHSV-ΔG). In the present study, to enhance the immunogenicity of VHSV replicon particles, we newly generated another form of VHSV replicon particles that can produce the transmembrane and C-terminal cytoplasmic region-deleted G protein in host cells (rVHSV-GΔTM), and compared the protective efficacy of rVHSV-GΔTM with that of rVHSV-ΔG through immunization of olive flounder (Paralichthys olivaceus). In addition, we evaluated the safety of rVHSV-GΔTM by the analysis of effects on wild-type VHSV replication. In the vaccine experiment, olive flounder immunized with rVHSV-GΔTM showed significantly higher titers of serum neutralization activity than fish immunized with rVHSV-ΔG suggesting that the G protein that is not only spiked on the viral envelop but also secreted extracellularly can contribute to the enhancement of adaptive humoral immunity. Moreover, fish immunized with rVHSV-GΔTM showed higher survival rates than fish immunized with rVHSV-ΔG, suggesting that the amount of G protein provided to hosts is an important factor for the enhancement of vaccine efficacy against VHSV disease. In a safety aspect, rVHSV-GΔTM could not replicate in infected cells, and significantly inhibited the replication of wild-type VHSV when co-infected, suggesting that rVHSV-GΔTM would not worsen disease progression caused by wild-type VHSV infection.


Assuntos
Linguado/imunologia , Septicemia Hemorrágica Viral/imunologia , Septicemia Hemorrágica Viral/virologia , Novirhabdovirus/genética , Replicon , Animais , Linguado/virologia , Deleção de Genes , Septicemia Hemorrágica Viral/prevenção & controle , Imunização , Novirhabdovirus/fisiologia , Proteínas Virais/genética , Vacinas Virais/imunologia , Replicação Viral
19.
Mol Microbiol ; 111(5): 1355-1366, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30767313

RESUMO

Members of the genus Shigella carry a large plasmid, pINV, which is essential for virulence. In Shigella flexneri, pINV harbours three toxin-antitoxin (TA) systems, CcdAB, GmvAT and VapBC that promote vertical transmission of the plasmid. Type II TA systems, such as those on pINV, consist of a toxic protein and protein antitoxin. Selective degradation of the antitoxin by proteases leads to the unopposed action of the toxin once genes encoding a TA system have been lost, such as following failure to inherit a plasmid harbouring a TA system. Here, we investigate the role of proteases in the function of the pINV TA systems and demonstrate that Lon, but not ClpP, is required for their activity during plasmid stability. This provides the first evidence that acetyltransferase family TA systems, such as GmvAT, can be regulated by Lon. Interestingly, S. flexneri pINV also harbours two putative partitioning systems, ParAB and StbAB. We show that both systems are functional for plasmid maintenance although their activity is masked by other systems on pINV. Using a model vector based on the pINV replicon, we observe temperature-dependent differences between the two partitioning systems that contribute to our understanding of the maintenance of virulence in Shigella species.


Assuntos
Regulação Bacteriana da Expressão Gênica , Plasmídeos/genética , Protease La/genética , Shigella flexneri/genética , Shigella flexneri/patogenicidade , Sistemas Toxina-Antitoxina , Acetiltransferases/metabolismo , Proteínas de Bactérias/metabolismo , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Protease La/metabolismo , Replicon , Shigella flexneri/enzimologia , Temperatura Ambiente , Virulência
20.
J Virol ; 93(7)2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30674625

RESUMO

Hepatitis C is a liver disease caused by the hepatitis C virus (HCV) affecting 71 million people worldwide with no licensed vaccines that prevent infection. Here, we have generated four novel alphavirus-based DNA-launched self-amplifying RNA replicon (DREP) vaccines expressing either structural core-E1-E2 or nonstructural p7-NS2-NS3 HCV proteins of genotype 1a placed under the control of an alphavirus promoter, with or without an alphaviral translational enhancer (grouped as DREP-HCV or DREP-e-HCV, respectively). DREP vectors are known to induce cross-priming and further stimulation of immune responses through apoptosis, and here we demonstrate that they efficiently trigger apoptosis-related proteins in transfected cells. Immunization of mice with the DREP vaccines as the priming immunization followed by a heterologous boost with a recombinant modified vaccinia virus Ankara (MVA) vector expressing the nearly full-length genome of HCV (MVA-HCV) induced potent and long-lasting HCV-specific CD4+ and CD8+ T cell immune responses that were significantly stronger than those of a homologous MVA-HCV prime/boost immunization, with the DREP-e-HCV/MVA-HCV combination the most immunogenic regimen. HCV-specific CD4+ and CD8+ T cell responses were highly polyfunctional, had an effector memory phenotype, and were mainly directed against E1-E2 and NS2-NS3, respectively. Additionally, DREP/MVA-HCV immunization regimens induced higher antibody levels against HCV E2 protein than homologous MVA-HCV immunization. Collectively, these results provided an immunization protocol against HCV by inducing high levels of HCV-specific T cell responses as well as humoral responses. These findings reinforce the combined use of DREP-based vectors and MVA-HCV as promising prophylactic and therapeutic vaccines against HCV.IMPORTANCE HCV represents a global health problem as more than 71 million people are chronically infected worldwide. Direct-acting antiviral agents can cure HCV infection in most patients, but due to the high cost of these agents and the emergence of resistant mutants, they do not represent a feasible and affordable strategy to eradicate the virus. Therefore, a vaccine is an urgent goal that requires efforts to understand the correlates of protection for HCV clearance. Here, we describe for the first time the generation of novel vaccines against HCV based on alphavirus DNA replicons expressing HCV antigens. We demonstrate that potent T cell immune responses, as well as humoral immune responses, against HCV can be achieved in mice by using a combined heterologous prime/boost immunization protocol consisting of the administration of alphavirus replicon DNA vectors as the priming immunization followed by a boost with a recombinant modified vaccinia virus Ankara vector expressing HCV antigens.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Hepacivirus/imunologia , Hepatite C/imunologia , Replicon/imunologia , Vírus Vaccinia/imunologia , Vacinas Virais/imunologia , Alphavirus/imunologia , Animais , Anticorpos Antivirais/imunologia , DNA/imunologia , Vetores Genéticos/imunologia , Imunização/métodos , Camundongos , RNA/imunologia , Vacinação/métodos , Vacinas de DNA/imunologia , Proteínas não Estruturais Virais/imunologia
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